.
where dij is the Euclidian distance between
patches j and i and α is the parameter of the negative exponential
dispersal kernel, which was set to 1 km−1 (see Jousimo
et al. (2014) for more details).Aj , is the square root
transformation of area (m2) of habitat patch j .
The Åland archipelago is highly fragmented and consists of the main
island and smaller islands that jointly form 16 regional districts of
similar size. To capture possible spatial variation among the regions
within the islands, we used regional district as a spatial unit. In our
sampling area, there were 10 regional districts (Eckerö (12), Finström
(41), Hammarland (38), Jomala (10) Lemland (37), Lumparland (49),
Maarianhamina (11), Saltvik (19), and Sund (46), with the number of
visited populations within each regional district given in parenthesis).